Donation after circulatory death – a new role for the anaesthetist?

Abstract

The Organ Donation Taskforce report Organs for Transplants was published just over 3 years ago. This made recommendations on actions necessary to increase the number of organs available for transplantation [1]. The report was commissioned as the UK had one of the lowest rates of deceased organ donation in Western Europe, only 13 donors per million of population. By comparison, Spain at this time had the highest rate of donors (35 donors per million of population), which had been achieved by systematically addressing barriers to donation over a number of years. The report made 14 recommendations to improve the rate of donation by 50% over 5 years. Most clinicians working in acute specialties will be aware of the large drive led by NHS Blood and Transplant (NHSBT) to implement all of these recommendations. In the financial year 2010–11, there were 1010 deceased donors in the UK [2] compared with 809 in 2007–8 [3], a 25% increase in 3 years. So there is evidence that addressing these issues is already having a beneficial effect on donation rates. Behind these headline figures, there is one striking trend. In 2007–8, there were 609 donations after brainstem death (DBD) and 637 in 2010–11, an increase of just under 5%. However, 3 years ago, there were only 200 donations after circulatory death (DCD) but last year there were 373, an 86% increase [2, 3]. Although DCD is not new (the first heart transplant more than 40 years ago by Christiaan Barnard was retrieved after the onset of asystole [4]), it is a relatively new process to most UK clinicians and there are a number of issues to be addressed as this programme is developed. Until recently, deceased organ donation in the UK has usually involved DBD. While the heart is still beating and perfusing the organs, surgery is carried out to retrieve the organs so that they can then be transplanted without undergoing significant warm ischaemia. However, if the organs can be perfused with cold preservation solutions soon after a patient dies in asystole, warm ischaemic damage can be minimised and the organs may still be suitable for transplantation, although the heart has stopped beating. There are two main categories of DCD: ‘controlled’, when death is expected, usually after withdrawal of life-sustaining therapy (Maastricht categories III and possibly IV); and ‘uncontrolled’, when death has occurred suddenly and unexpectedly (Maastricht categories I, II and V) [5]. Other than in a few trial sites, ‘uncontrolled’ DCD is not routinely undertaken in the UK although is quite common in other countries, notably Spain [5]. There are very significant ethical, legal and practical issues that need to be clarified for healthcare professionals and the public alike, before ‘uncontrolled’ DCD becomes routine in this country. (For a start, surely there must be a better term than ‘uncontrolled’ DCD? In this ‘media savvy’ age, there will be few supporters of any ‘uncontrolled’ medical procedure, either from clinicians or from patients.) So what does today’s anaesthetist need to know about controlled DCD, as it becomes more common? In a survey, 90% of the general public were in favour of the deceased donation/transplant programme [6] and more than 18 million people have now joined the organ donor register [7]. However, only a small proportion of deaths each year will be diagnosed by brainstem death criteria. So, if death is expected and can be predicted and our patients want to donate their organs after death, then we, their clinicians, should try to facilitate their wishes. A fundamental principle of a controlled DCD programme, in our opinion, starts before any consideration of donation. That is, the decision to withdraw life-sustaining treatment in the best interests of the patient has already been made and accepted by all involved in the patient’s care, including the ICU medical and nursing staff, the admitting team, the patient (if able) and the patient’s next of kin, regardless of the possibility of donation. While the patient is still being treated with ‘curative’ intent, all care should be focused on improving the patient’s medical condition. However, once the decision to withdraw this life-sustaining treatment is made, donation should be a normal part of end-of-life care. In brief, before withdrawal of the life-sustaining treatment occurs, the patient’s wishes about donation should be explored by checking the organ donor register and discussion with the patient’s next of kin. Usually, this is best undertaken by the Specialist Nurses – Organ Donation (SNODs – previously known as Donor Transplant Coordinators). They have the time needed and also the specialist knowledge to answer questions from the family. The local hospital teams remain involved, as they are still responsible for the overall care of their patient. The SNOD will also be able to check the suitability of the patient for donation and liaise with the transplant teams. If donation is believed to be what the patient wants and his/her organs are suitable for transplantation, then the retrieval team needs to come to the referring hospital. In the meantime, life-sustaining treatment should continue. The Department of Health has issued legal advice about how to manage treatment decisions in this intervening period [8]. The guiding principle is that treatment is provided in the patient’s best interests, which includes their social, emotional, cultural and religious interests, as well as considering their direct medical needs. So, if a patient wants to donate organs after death, it would be in his/her best interest to ensure that the organs are transplanted in the best possible condition. Therefore, simple treatments that help maintain organ viability without causing or risking significant harm or distress to the patient can be provided, e.g. increasing inspired oxygen concentration, titrating vasoactive drugs to maintain the current blood pressure or continuing mechanical ventilation. However, treatments that might cause or risk significant harm or distress to the patient should not be undertaken; examples from the guidance are cardiopulmonary resuscitation (CPR) and systemic heparinisation. These are medical decisions and therefore should be judged on an individual basis, considering the patient’s condition and wishes. With the retrieval team ready in the hospital, life-sustaining treatment can then be withdrawn. Depending on the layout of the hospital this may require the transfer of the patient to the operating theatre suite (most commonly an anaesthetic room) for the withdrawal of therapy, as once death is diagnosed the cold perfusion of organs needs to occur rapidly. The patient will need to be constantly monitored and observed and if the family are in attendance, they will also require appropriate support as usual. Providing this care outside of the walls of an ICU can be a challenge and requires advance planning, involving ICU, anaesthetic and theatre staff, as well as the SNODs. Recent meetings of clinical leads for organ donation have shown that there is considerable variation among clinicians about how care is withdrawn. Clearly, individual patients’ circumstances must be considered and the process carried out accordingly. However, some clinicians never extubate/decannulate the airway, whereas others will remove artificial airways along with the other life-sustaining treatments, in the best interests of the patient, as to leave these tubes in place is judged to prolong the dying process. In the context of donation, leaving these artificial airways in place may also prolong the functional warm ischaemic time and thus preclude transplantation. In our opinion, it is ethically and legally acceptable to extubate the tracheas of such patients, but many clinicians feel uncomfortable about this. It is essential that more consistent management in this area is pursued. Diagnosis of death is carried out according to the same principles as diagnosing death by cardiorespiratory criteria as laid out in the Academy of Medical Royal Colleges Code of Practice [9]. To ensure death is confidently diagnosed promptly and without unnecessary delay, absence of the circulation for 5 min should be confirmed using an arterial line if present (or using echocardiography) or alternatively, asystole on the ECG, as digital palpation of a central pulse in not deemed sufficiently reliable. Agreement that there should be no intervention to restart the circulation (i.e. no attempt at CPR) is a prerequisite for diagnosing death after cardiorespiratory arrest. There must also be no intervention that could potentially restore cerebral circulation after death is diagnosed. This fundamental point needs careful consideration in relation to a number of events that can occur in the process of organ retrieval. After death is diagnosed, the patient is promptly transferred into the operating theatre for the transplant team to start the process of organ retrieval. Large cannulae may be sited and cold non-blood preservation fluids circulated any time after death is diagnosed. Blood-containing fluids, which could potentially restore cerebral perfusion or restart the heart in situ, should not be used unless the cerebral circulation and coronary arteries have been completely occluded [10]. Exclusion of the cerebral circulation requires clamping of the aortic arch, as balloon occlusion catheters are not believed to be reliable enough. In the case of lung donation, if the patient’s trachea has been extubated before death then re-intubation is required to reduce the risk of aspiration [11]. Who performs this remains controversial; there are concerns that this procedure could somehow be a conflict of interest if performed by an anaesthetist from the local hospital. The UK Donation Ethics Committee has sensibly concluded that there is no ethical reason why this could not be carried out by the local hospital staff [12]. However, logistical barriers may be more important. As well as intubation to protect the lungs from aspiration, transplant surgeons prefer the lungs to be re-inflated [11]. Because of concerns that rhythmical mechanical ventilation could potentially restart the heart, this should not occur until the cerebral circulation is excluded. A single recruitment manoeuvre followed by a low level of continuous positive airway pressure has been suggested as acceptable [10]. The implications of such procedures to facilitate organ retrieval need more clarification. However, it is clear that these procedures, although not technically difficult, require very specific knowledge to ensure that they are carried out at the appropriate time in the correct circumstance. It is difficult to expect every anaesthetist in the local hospital to be fully aware of all these circumstances in a rapidly changing area of practice, especially as donations might only happen once or twice a year – and often in the middle of the night, when support from other experienced colleagues may be limited. We strongly support the idea that the retrieval team should include an appropriately trained, specialised anaesthetist to facilitate the organ retrieval. This, in fact, was one of the suggestions from the Organ Donation Taskforce [1] and according to the recent National Standards for Organ Retrieval from Deceased Donors published by NHSBT [11], this is still being explored with national bodies. But if such posts existed, would it be possible to recruit into them? These anaesthetists would have to participate in a robust 24/7 rota, be ready to leave the retrieval centre within 1 h, and travel long distances to work in unfamiliar surroundings, mostly during antisocial hours. There are 13 retrieval teams nationally and each would need at least six people per rota to meet European Working Time Regulations. Is such a system sustainable? Would it have to be staffed only by consultant anaesthetists, or could senior anaesthetic trainees participate as part of a transplantation fellowship? Do the personnel actually have to be medically trained anaesthetists? As mentioned previously, none of the procedures is technically difficult; it is more that the management and knowledge required is highly specialised. Could this be a role for other healthcare practitioners appropriately trained with the necessary intubation skills, physiological and pharmacological knowledge – and probably most important in the case of DCD, awareness of the process of organ donation, retrieval and transplantation? As numbers of deceased donors continue to increase and as financial constraints place greater pressures on individual hospitals, with potentially fewer tiers of local on-call rotas, it appears to us even more important than ever to consider whether the organ retrieval team should include specialist ‘anaesthetic’ personnel, both to ensure high standards of care and to solve practical difficulties. Despite initial concerns about DCD [13], it seems that the controlled DCD programme is working well in the UK. More than a third of deceased donors last year were DCDs and many of the legal, ethical and professional concerns are being addressed [8, 10, 12]. The UK anaesthetic community, and those who fund it, must now consider carefully how we want to provide this final, important step in our patients’ care, to ensure that their gift of donation results in the maximum benefit for our other patients, the transplant recipients. ACG is the Clinical Lead for Organ Donation and AJH has been the Chairman of the Organ Donation Committee at Imperial College NHS Trust. AJH is the Hon. Secretary of the AAGBI and an ex-officio member of the Editorial Board of Anaesthesia. ACG is an National Institute for Health Research (NIHR) Clinician Scientists award holder, and both authors are grateful for funding from the NIHR comprehensive Biomedical Research Centre funding stream.